Konarka, Dow Target Bigger Roles for Plastics in Solar Power

Third-generation
solar technologies use advanced materials, including conductive plastic, to
achieve acceptable efficiencies and design capabilities not possible with
silicon.

Two of the
cornerstone programs in the federal Solar America
Initiative (SAI) are building-integrated organic photovoltaic technologies
being developed by Konarka, of Lowell,
MA and Dow Chemical of Midland,
MI. Electricity from the grid costs abut 8 cents per kWh now. Power from currently available solar
technology is triple that. The SAI wants its projects to deliver grid power for
less than 10 cents per kWh by 2015.

One novel but pricey application is a sun umbrella fitted with flexible solar panels
that provide electricity on the spot for laptop computers, cell phones or other
consumer applications. They're already being used on outdoor patios of coffee
shops in sunny locations and on patios near swimming pools.

"These
first units are selling for $10,000," says Joe McKenna, executive vice
president of SkyShades of Longwood, FL.
"I hope to drive the price down to $7,500-$8,000 as volume increases;
the first few are always a bit more expensive. Our umbrella units on their own
sell for $5,200 as they are a structure and must be anchored to a suitable
foundation."

The
electricity in the flexible solar panels comes from Power Plastic, a patented
and highly secretive material. A review of Konarka patents shows that much of
its work has focused on conjugated polymers that behave as metallic conductors and
semiconductors. The polymers include at least the following: polythiophenes, polyalkylthiophene,
polydihexylterthiophene (PDHTT), polythienylene vinylenes and polyfluorene
derivatives.

Photovoltaic
cells are produced using continuous web manufacturing techniques in which a
polymeric system is applied in a tree-like geometry to a substrate and subsequently in a roll-to-roll type manufacturing process.
The substrate is any plastic that can be metalized in a web process. One
preferred material is polyester. Other
candidates include polycarbonate, acrylic and polystyrene. Efficiency can be
improved through application of a
coating that will prevent the reflection of certain types of light. Some
producers also further enhance performance through doping with conductive
materials. The photovoltaic cells can also be applied through other printing systems.

"Konarka's
innovations lie within its materials, manufacturing processes and form factor
for its light-activated power plastic," says Dan Williams, vice president of
business development at Konarka. "We've brought proven coating and printing
know-how from the chemical, photographic film and flexible electronics
industries to energy via a new class of nano-structured materials."

Konarka's
material is two-thirds less expensive than traditional silicon-based solar
materials. It's also very light â only one to two ounces per square foot. Konarka
recently announced a new strategic collaboration with Total, a major oil
company based in Paris.
Total is investing $45 million in Konarka, becoming its biggest shareholder. Total clearly sees some synergies with its
businesses, which include Cook Composites and Polymers, which develops printing
inks as well as other compounds.

The current
demonstrated efficiency of the system is 6 percent â good but not really good
enough. Typical silicon-based solar systems have efficiencies of around 15
percent. Konarka says its
electrical output will cost less than 10 cents per kWh, making its
material ideal for widespread use as a building-integrated photovoltaic.

As
previously reported
by Design News, another major player in this technology arena is Plextronics, a
Pittsburgh-based spinoff from Carnegie
Mellon University
that opened its first manufacturing development line in January.

The small-scale manufacturing facility will print
solar demonstration modules with printable solar inks made from conductive
polymers, such as those used by Konarka. The modular design of the line will
also permit the company to evaluate new processes that will maximize the
performance of those inks.

"This line is focused on stimulating
broad market commercialization of our innovative ink systems," says Andy
Hannah, Plextronics' President and CEO.
"Sometimes, especially in an emerging market like printed
electronics, a company must be willing to take the initial steps to demonstrate
to the marketplace what's possible with new technology."

Another
major player is Dow
Chemical, which is receiving $20 million from the Solar America Initiative
Pathways Program conducted by the U.S. Department of Energy.

Dow is
leveraging its encapsulation and roofing knowledge to develop solar roofing
shingles. Late last year, Dow installed a 1,350-ton tandem clamp injection
molding machine at its Michigan Operations manufacturing site in Midland, MI
to develop technology that will integrate flexible solar panels into plastic
roofing.

Current
silicon-based solar cells are packaged within heavy glass panels on rooftops.
They are expensive, hard to install and produce electricity that is significantly
more expensive than electricity sold over the grid.

"Dow's
innovative technology is based on a much more cost-effective photovoltaic
material called CIGS and these cells are âpackaged' within the roofing
product creating a âsolar shingle,'" says Bob Cleereman, Sow's senior technical
director of building-integrated photovoltaic technology.

CIGS, which
is composed of copper, indium, gallium and selenium, is used as light absorber
material for thin-film solar cells. More than two dozen companies are working
with CIGS technology, and some are struggling to achieve workable efficiency
levels.
Dow's original partner in the SAI project was a California-based company called
Miasloe, which at one time had been a leader in CIGS development. But the company missed key objectives and was
replaced in the SAI project last year with Global Solar Energy, which last year opened a CIGS factory in Arizona.
The company expects to produce 20 megawatts of the film at the plant this year.

"We are
collaborating with Global Solar Energy because throughout our search for a
solar material provider, it was the only company able to supply a qualifying
flexible CIGS material that meets our needs and the requirements of the SAI,"
said Dow's Cleereman. "Copper Indium Gallium diSelenide has proven to be the most efficient,
cost-effective thin-film technology for building-integrated photovoltaic applications."

Global Solar is the only
company in full-scale production of CIGS cells on flexible substrates and has
achieved a record-setting average 10-percent solar cell efficiency, a
requirement for the SAI program. The goal of the SAI is to create solar
electricity cost effectiveness with grid electricity within six years.

Dow would
not discuss specifics of its technology, but the giant injection molding
machine is a big clue. Dow may try to integrate the solar panels into a molded
plastic structure, just the way a label is molded into a dashboard inside a
mold cavity. It's an exciting idea if the solar material can be web-fed into
the tool. That creates very high-volume production economics.

It's not
clear what thermoplastic materials may provide the structure for the
"molded-in" solar panel. One candidate is thermoplastic olefin, which is a
major material in the roofing business (Stevens Roofing Systems and Geomembrane
Systems) that Dow acquired last year. Although Dow has been trying to reduce its
profile in volume thermoplastics, it remains a major producer of TPO, which is
also widely used in automotive applications.

The Konarka
project is very interesting as a leading edge technology, but the Dow project
has the promise to be a major game-changer in the not-too distant future.

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